Home | Business News | Browse by Publication | M | Michigan Academician

Biochemistry/molecular Biology.

Article Excerpt
Mycobacterium chlorophenolicum and Its Ability to Survive in the Presence of Pentachlorophenol. Rachael Glassford, and Darin McCarthy, Calvin College, Department of Chemistry and Biochemistry, Grand Rapids, MI 49546

Pentachlophenol (PCP), a wood preservative banned in 1987 due to its toxicity, continues to contaminate sites around the world and presents an environmental cleanup challenge. M. chlorophenolicum has been isolated from PCP-contaminated sites and has the ability to survive in the presence of PCP, despite the fact that this toxin interferes with oxidative phosphorylation. Out goal is to understand the mechanisms by which M. chlorophenolicum both survives in the presence of, and degrades PCP Although PCP induces a lag phase in M. chlorophenolicum growth, PCP-treated cells grow at the same rate as control cultures. However, PCP inhibits growth in control mycobacteria, M. smegmatis and M. phlei. In addition, cellular respiration in M. chlorophenolicum is significantly inhibited at high concentrations of PCP, but is uncoupled in control strains. The effect of PCP on respiration is pH dependent; oxygen consumption is inhibited more strongly at low pH. These results indicate that M. chlorophenolicum is uniquely able to survive in the presence of PCP because it enters a dormant state at high PCP concentrations, thus not wasting energy that would be lost due to uncoupling of oxidative phosphorylation.

Preliminary Studies on the Dechlorination of Tetrachloro-l,4-hydroquine by Mycobacterium chlorophenolicum PCP-1. Arianne Folkema, Brad Veldkamp, Lia Wisniewski, and Darla McCarthy, Calvin College, Department of Chemistry and Biochemistry, Grand Rapids, MI 49546

We are characterizing a tetrachloro-1,4-hydroquinone (TCHQ) dehalogenating enzyme from Mycobacterium chlorophenolicum PCP-1, a gram-positive bacterium that catabolizes pentachlorophenol (PCP). The PCP catabolic. pathway in M. chlorophenolicum PCP-1 begins with the para-hydroxlyation of PCP to form TCHQ. The next step in the catabolic pathway, catalyzed by TCHQ dehalogenase, has been proposed to involve hydroxylation of TCHQ to form tnchloro-l,2,4-trihydtoxybenzene (TTHB). However, our preliminary results indicate that a reductive dehalogenation occurs, producing trichloro-l,4-hydroquinone. Such a reductive dehalogenation is known to be catalyzed by the TCHQ dehalogenase isolated from Sphingobium chlorophenolicum. The reducing equivalents for the reductive dehalogenation catalyzed by the S. chlorophenolicum TCHQ dehalogenase come from the co-substrate glutathione. However, mycobacteria are known NOT to synthesize, or even to utilize, glutathione. Indeed, out results indicate that the activity of TCHQ dehalogenase from M. chlorophenolicum PCP-1 is not dependent on glutathione. We are currently attempting to determine the identity of the reducing co-substrate employed by the M. chlorophenolicum PCP-1 TCHQ dehalogenase.

Identification of Host and Bacterial Proteins Present Inside Murine Abscesses Infected by Staphylococcus aureus. Marcella Luercio, University of Michigan-Flint, Biology Department, Flint, MI 48502, Eric Skaar and Victor Torres, Vanderbilt University, Department of Microbiology...